grendel said:
So these substances have always been here,since the begining of time?
Not necessarily...
The phrase, "...since the beginning of time..." complicates matters considerably, so let's replace it with the phrase, "...for a very, very, very long time...'. By the phrase, "...a very, very, very long time...", I mean eons and eons.
Some substances have been around for eons and eons, albeit in a much "dilute" form --- like platinum, gold, silver, mercury, arsenic, tin, chromium, copper, aluminum, etc... Man has taken it upon himself to "concentrate" these metals. Mercury, for example, was found to kill certain bacteria, so man compounded it with other substances, and created a dilute poison. However, until rather recently, man did not realize he was gradually poisoning himself... In the meantime, such substances have been removed from the marketplace. Teeth are no longer filled using silver--mercury amalgam.:v:
"Way back when," wood was preserved by impregnating it with creosote using the Boucherie Process, which was developed in the mid--1800s. The creosote used in wood preservation is produced by the high temperature carbonization of wood and coal and consists principally of aromatic hydrocarbons plus some tar acids and bases. Without going into detail: People knew that creosote, was "bad stuff." It also "stank," and it could not be painted. So an alternative was sought.
Years ago (probably after WWII) it was found that the microbial decomposition of wood could be slowed or thwarted by treating it with pentachlorophenol, aka. "Woodlife." Up until 1984 Pentachlorophenol or “Penta” (C6Cl5OH) was one of the most heavily used all-purpose pesticides in the U.S. Penta was produced using aluminum chloride or ferric chloride as catalysts for the chlorination of phenols. Wood treated with Woodlife did not stink, and it could be painted. Additionally, the microbial decomposition of partially decomposed wood could be halted, and the damaged areas repaired. However, it was found that minute quantities of highly toxic substances, known as "dioxins," were also formed as unintentional by-products of pentachlorophenol production. The wood preservative was found to contain "dioxin" as was "Dial" soap, some deodorants and shampoos, etc. They have, since, all been removed from the market place: banned!
Dioxins are created in many other industrial processes involving chlorine, such as waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching. BTW: Dioxin was the primary toxic component of Agent Orange; and it was found at Love Canal in Niagara Falls, NY. It was the cause for the evacuations at Times Beach, MO and Seveso, Italy (Many children there developed "Chloracne" and will be deformed for life.).
In the meantime, another means of wood preservation was developed. If you have a wood deck at home, or an older bulkhead, dock, or part of your home is supported by "green wood pilings," then the lumber used was probably treated with "CCA." CCA, another type of wood preservative, is made up of the oxides or salts of copper, chromium, and arsenic. The arsenic and copper are toxic to insects and fungi that prey on wood, while chromium is used to bond the two elements to the wood's cellular components. It was known, early on that CCA--treated lumber posed a definite health threat: Most lumberyards, for example, would NOT cut the stuff, under any circumstances! In the meantime, it has been taken off the market --- except for "professional use" [(?!)], and it is considered to be a major contributor to non--point source arsenic pollution. Much "durable" playground equipment that was constructed years ago using this material has been disassembled and disposed of; the soil of the playgrounds had to be "remediated" --- the arsenic--laden soil removed...
So, Grendel, although many of the elements now found on the periodic chart, such as platinum, gold, silver, mercury, arsenic, tin, chromium, copper, and aluminum, have been "around" for eons and eons, their natural concentrations were, for the most part, "low" and, thus, did threaten flora nor fauna on a large scale basis. Man has concentrated these metals, reacted them with other substances, such as the nonmetal "chlorine," to create compounds that are not commonly found in nature, or do not occur there at all. In all cases, whether it was creosote, pentachlorophenol, dioxin or CCA, matter was neither created nor destroyed: It was merely "converted" from one form to another.:eng101:
All of this nasty "stuff" gradually finds its way into the ground, our streams, our rivers and our oceans. If, in its travels, it is not "bioconverted" into less hazardous substances, or is not "bound," chemically, to some substrate, it ultimately finds its way into the food chain --- seafood. Bottom feeders (
Catfish dinner, anyone?) are most exposed, since the "nasties" usually "settle out.":jeffd:
ebsi
P.S.: The most toxic "dioxin" is 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD. The toxicity of other dioxins and chemicals like PCBs, that act like dioxin, are measured in relation to TCDD. Some public health experts feel that public health impact of dioxin may rival the impact that DDT had on public health in the 1960's. According to the EPA, not only does there appear to be no "safe" level of exposure to dioxin, but
levels of dioxin and dioxin-like chemicals have been found in the general US population that are at or near levels associated with adverse health effects. :jeffd:
e.
______________________________
"An expert is a person who has made all the mistakes that can be made in a very narrow field."
...and the alcohol contained therein is not just "toxic" to the yeast cells that produce it, but also to the humans who consume it!